Every lobster trap set off the coast of Maine must carry a small plastic tag, usually stamped with a license number, a year and a fishing zone. A team based at the University of the Azores has used those tags, along with the gear’s distinctive design, to identify 1,577 pieces of North American lobster gear. All of it washed up on two islands in the middle of the North Atlantic, and hundreds of the pieces could be traced to the country, state or fishing zone they came from.
Between 2017 and 2025, the team and a group of volunteers picked up the items on the southern coasts of Faial and Pico. Of the trap tags they could read, 63 percent came from the United States and 37 percent from Canada. Among US tags whose state could be identified, 80 percent were from Maine.
The tags carried registration years from 1983 to 2023. Among 130 US tags with both dates known, registration came an average of about 13 years before collection.
The study, led by Christopher K. Pham, head of the marine litter research group at the University of the Azores, was published in Environmental Monitoring and Assessment on 27 August. The evidence is a count of what people found, not a survey. Items were gathered opportunistically on beaches known to collect stranded debris, so the paper makes no estimate of how much lobster gear is on Azorean shores.
A return address on every trap
US and Canadian rules require a tag on every lobster trap. US tags are replaced at the start of every fishing season, while Canada issues both single-year tags and multi-year tags valid for up to three years. The details vary between the two countries, but a tag typically carries the license number, the year and the fishing area.
Those markings are what made the study possible. Much of the plastic washing up on remote islands is too fragmented to tell what kind of activity it came from, the paper notes. Speaking to Euronews, Pham pointed out that a trawl net could have been used in Greenland or in Brazil. For most other beach waste, he said, the team almost never knows the precise origin. A readable lobster tag names its country and year, and often its state or province.
The team began noticing the numbered tags while monitoring beach litter, worked out what the numbers meant, and then asked local people and colleagues to bring any they found. At least ten volunteers kept sending material every month, Pham told Euronews.
The tags that could be read
Of the 1,577 items, 824 were trap tags and 601 were escape vents, the plastic panels that let undersized lobsters and other unwanted animals slip out of a trap. The other 152 included trap corners, funnels, closures, rubber bands, runner brackets and bait-bag cleats. The inscriptions were legible on 630 of the tags: 399 from the United States and 231 from Canada.
The US tags were easy to place. A state could be read on 365 of them, and Maine accounted for 80 percent, which by our count works out to roughly 290 tags. Massachusetts accounted for 11 percent, and the remaining 9 percent came from other states, including Rhode Island, New Hampshire, Connecticut and North Carolina.
Where the management area could be read, 240 of 383 US tags came from Area 1, the nearshore Gulf of Maine zone off Maine, New Hampshire and Massachusetts as far south as the Cape Cod Canal.
The Canadian tags were much harder. A province could be identified on only 20 percent of them, 45 tags in all, and 29 of those were from Newfoundland and Labrador. A fishing area was legible on 29 Canadian tags, and most of those came from Lobster Fishing Area 34 in southwestern Nova Scotia, a point Pham confirmed in an email.
The escape vents point the same way. Among the 199 vents whose country could be identified from their inscriptions, 68 percent were American and 32 percent Canadian.
Newfoundland or Nova Scotia, depending on who reported it
The small Canadian subsets have produced two different stories. Euronews reported that the Canadian tags came from Newfoundland and Labrador. CBC News reported that the Canadian gear was mostly traced to Lobster Fishing Area 34 in Nova Scotia.
Euronews’s version matches the 29 Newfoundland and Labrador tags among the 45 with a readable province. CBC’s matches the majority of a second tally that also happens to be 29: the tags with a readable fishing area. CBC also presented the Canadian share, “over a third,” as applying to all of the more than 1,500 pieces; in the paper, the 37 percent figure describes only the 630 tags that could be read.
Neither report describes the Canadian tags as a whole. Of the 231 legible ones, most could not be placed in any province or fishing area.
Checking the 3,000 km on a map
The paper describes the fishery as operating “more than 3,000 km away.” Science Blog checked that against a map, measuring great-circle distances, the shortest route over the curve of the Earth, from Horta on Faial. Portland, Maine, is about 3,500 km from Horta, and so is Chatham on Cape Cod. Yarmouth, at the southwestern tip of Nova Scotia near Lobster Fishing Area 34, is about 3,160 km. Madalena, on Pico, adds less than 10 km to each figure.
The figure holds for Maine, Massachusetts and southwestern Nova Scotia, which account for most of the traceable tags. It does not hold for Newfoundland and Labrador. The island of Newfoundland and the southern Labrador coast lie about 2,200 to 2,700 km from Faial in a straight line, with the Avalon Peninsula around St. John’s closest. Those are straight-line figures, and a tag riding the clockwise currents would travel farther.
From under two years to 36
The tags’ dates add a second clue, about time rather than distance. The 13-year average, give or take seven years, hides a wide spread. Of the 130 US tags behind it, four were found less than two years after registration and six more than 20 years after. The paper’s abstract gives the average as 12 years; the 13 here comes from the results section.
The four tags found in under two years show that some plastic makes the crossing fast. The North Atlantic’s currents circulate clockwise, carrying material from west to east, Pham explained to Euronews. The paper says its findings back up earlier modeling studies indicating that much of the debris reaching the Azores starts on the east coast of North America and is carried across by the Gulf Stream. One of those studies, a 2024 paper in Marine Pollution Bulletin that Pham co-authored, is described in the new paper as showing that North American lobster tags work as tracers of plastic drifting across the Atlantic from northwest to northeast.
The old dates matter for a different reason. Three tags were recovered 36 years after they were registered. The researchers write that markings still legible after prolonged exposure at sea are evidence from the field, not the lab, that these items neither sink to the seafloor nor break apart quickly, at least over a couple of decades. The tags are made from very high-quality plastic, Pham told Euronews, and if the team keeps looking it will very likely find items that are perhaps even older.
Tags tossed overboard and vents built to break free
About 3 million lobster traps are set in US waters each year and about 2 million in Canada, according to the paper. It puts the annual loss rate at 0.5 to 2 percent, citing a 2021 Nova Scotia study. On those figures, the two fleets together lose roughly 25,000 to 100,000 traps a year. That range is our own arithmetic from the paper’s inputs, not a number the paper states.
Not every tag on an Azorean beach came off a lost trap, though. Because tags are swapped out every one to three years, the paper notes, old ones are often discarded at sea, either deliberately or by accident. Tags can also break off easily while traps are being hauled.
The escape vents have a less obvious explanation. The rings that hold them in place are designed to break down over time, so that a lost trap eventually sheds its vent and anything caught inside can get out. The aim is to stop ghost fishing, in which abandoned gear keeps catching and killing animals long after anyone is tending it. It also means some of the plastic reaching the Azores was built to come loose.
The limits of a beach count
Because the collection had no standard measure of search effort, the paper says, density estimates were impossible, and the finds come from the southern coasts of just two islands. Without density estimates, a beach count cannot show whether the flow is growing.
A registration year is also not the date a tag went into the sea. A 1983 tag shows when it was issued, so the 13-year average describes the time from registration to collection, not the time spent drifting.
The country shares only describe the tags that could be read. By our count, nearly a quarter of the 824 tags had no legible inscription. The Maine share needs a qualifier too: the paper’s abstract gives 76 percent, while the results section gives 80 percent of the 365 US tags with an identifiable state, and this article uses the results figure. Either way it describes US tags only. By our count, Maine’s tags make up a little under half of the 630 legible tags from both countries.
The paper does not claim that lobster gear dominates Azorean beach litter either. CBC News reported that it makes up only a fraction of the trash washing ashore. What sets it apart is that it can often be traced to a place and a year.
Marking gear so its source can be named
The authors call for better ways of attaching tags, programs to recover lost gear, workshops for fishers, collection bins at ports and incentives for fishers to hand in old gear. They also argue that gear-marking practices like those in the United Nations Food and Agriculture Organization’s 2019 voluntary guidelines on marking fishing gear can help identify where pollution comes from.
Lobster tags show what that kind of marking makes possible. Because the US and Canada require them, the beaches of Faial and Pico now hold a record that much of the plastic on remote beaches is too broken up to give.
In a statement to CBC News, Canada’s Department of Fisheries and Oceans said commercial harvesters must report lost gear and that the federal government is allocating an additional C$15 million to retrieve ghost gear from Canadian waters. Pham’s message in his Euronews interview was aimed at authorities in the United States and Canada. “It is important that you take action to reduce this flow of plastic into the sea, because people who have nothing to do with the pollution are becoming victims,” he said.
Whether that flow is growing or shrinking, and what share of overall plastic pollution it represents, is what the team wants to find out next, through a more systematic analysis, Pham told Euronews.